1. Field of the Invention
This invention relates to trays made of cardboard, corrugated board or similar lightweight foldable sheet material.
2. Description of the Related Art
Such trays are often used for storing and transporting fresh foodstuffs such as fruit and vegetables and are then required to be stackable one upon another in stable fashion. To achieve stable stacking, i.e. reliable location of each tray against lateral movement relative to the one below it in a stack, it is known to form the tray with integral stacking lugs upstanding from the tops of its side walls, for engagement in recesses at the edge of the base of a similar tray stacked on top of it. Such a stacking lug can be a simple, single thickness, upward extension of a wall panel, but a lug of this kind is likely to bend and/or fray quite quickly during use and is therefore not satisfactory. A substantial improvement is provided by forming a stacking lug as a folded over, double thickness, integral upward extension of the respective panels of a folded over, double thickness, side wall, as in GB-A-2279331. With this arrangement however, in order to provide the necessary sheet material between the wall panels to form the stacking lug, a comparatively wide strip of sheet material has to be provided extending along the top of the wall, integrally interconnecting the wall panels. Only a small part of the length of this strip is used to create the stacking lug, and thus a substantial wastage of sheet material occurs.
According to the present invention there is provided a tray made of cardboard, corrugated board or similar lightweight foldable sheet material, having a base, a side wall, and a stacking lug extending upwardly above the top of said side wall, the side wall being of double thickness formed of hingedly interconnected inner and outer side wall panels, the outer one connected to the base, folded over face to face, and the stacking lug comprising an integral upward extension of only the outer one of said side wall panels, folded over inwardly to be of double thickness and held to the inside of the said wall.
As such a stacking lug is integral with only the outer side wall panel it is no longer necessary to provide sufficient sheet material between the panels to create it. Instead, substantially all of the material to form the lug can be taken from the inner side wall panel by releasing the lug material therefrom.
The stacking lug may be held to the inside of its associated side wall in any convenient fashion, such as by gluing or stapling. In a preferred form of the invention however the stacking lug is held to the wall by having part thereof trapped between the said inner and outer wall panels. Again preferably, the lug may be formed with two opposite laterally protruding wing portions which are trapped as aforesaid.